ipmi: Reset response handler when failing to send the command

When failing to send a command we don't expect a response. Clear the
`null_user_handler` like is done in the success path.
Signed-off-by: Markus Boehme <markubo@amazon.com>
Message-Id: <1599495937-10654-1-git-send-email-markubo@amazon.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>

drivers/char/ipmi/ipmi_msghandler.c

@@ -2433,7 +2433,7 @@ static int __get_device_id(struct ipmi_smi *intf, struct bmc_device *bmc)
 
 	rv = send_get_device_id_cmd(intf);
 	if (rv)
-		return rv;
+		goto out_reset_handler;
 
 	wait_event(intf->waitq, bmc->dyn_id_set != 2);
 
@@ -2443,6 +2443,7 @@ static int __get_device_id(struct ipmi_smi *intf, struct bmc_device *bmc)
 	/* dyn_id_set makes the id data available. */
 	smp_rmb();
 
+out_reset_handler:
 	intf->null_user_handler = NULL;
 
 	return rv;
@@ -3329,6 +3330,7 @@ static int __scan_channels(struct ipmi_smi *intf, struct ipmi_device_id *id)
 			dev_warn(intf->si_dev,
 				 "Error sending channel information for channel 0, %d\n",
 				 rv);
+			intf->null_user_handler = NULL;
 			return -EIO;
 		}